In some cases, you may be allowed to Cash Out your bet before the market goes live. In some other situations, once you have placed your bet and it has been accepted, you cannot cancel it. Be sure to always make sure you have the correct bet before submitting it.
To edit a bet, press and hold the bet to open the menu screen. Choose Edit Pick, and make updates to the risk, spread, or odds. Choose Save in the upper corner to complete your changes.